| Abstract |
Given an electrical traction vehicle for 16 2/3 Hz mains with impressed voltage inverters operating asynchronous motors, the huge 16 2/3 Hz - 15 kV main transformer can be substituted by power electronics plus a 400 Hz transformer. The new power transmission system consists of the following parts: 16 2/3 Hz - 15 kV RMS bridge rectifier, bridge type voltage source inverter operating at 400 Hz - 15 kV and a 400 Hz step down transformer, 400 Hz rectifier, dc chopper, capacitor and filter components for the impressed voltage three phase inverters, asynchronous motors. The high voltage inverter provides voltage blocks - modulated by 16 2/3 Hz - to the 400 Hz transformer, which is far smaller and has less losses than its 16 2/3 Hz counterpart. Headed by a bridge rectifier on the secondary, the dc chopper is controlled on achieving a nearly sinusoidal current draw from the mains. The rated total power of an electrical traction vehicle can be increased by nearly 10 % at constant axle load and total volume; electrical losses are reduced and a high power factor can be obtained. |
